Handpieces for dental purposes



Feb- 52 1963 E. HoFFMElsTl-:R ETAL. 3,076,267

HANDPIEcEs FOR DENTAL PURPOSES 3 Sheets-Sheet 1 Filed Jan. 2, 1959 E. HoFFMExsTER ETAL 3,076,267

HANDPIEcEs FOR DENTAL PURPOSES Feb. 5,=. 1963 5 Sheets-Sheet 2 Filed Jan. 2, 1959 Feb- 5, 1963 E. HoFFMEls'rER ETAL 3,076,267

HANDPIECES FOR DENTAL PURPOSES 3 Sheets-Sheet 3 Filed Jan. 2, 1959 E Kw?? United States Patent() M 3,976,267 HANDIIECES EGR DENTAL EURISES Erich Hodrneister and Kurt Rohm, Eiberaeh (Riss), Ger" many, assignors to Alois Kaitenbach and Erieh Hottrnei'ster, both of Biberach (Riss), Germany, the responsible partners of Kaltenbach 8c Voigt, a Ifiornmandit gesellschaft Filed Ian. 2, 1959, Ser. No. 7hd5tl Claims priority, application Germany Jan. 9, 1958 21 Claims. (Qi. :i2-26) This invention relates to handpieces for dental purposes.

In known 4handpieces for dental purposes which are driven by an air turbine, the air turbine is arranged at the rear end of the handpiece. This means that the driving shaft, which rotates at a high speed, extends through the entire handpicce as far as the nose of the handpiece,

possibly with the interposition of a coupling. With the very high speeds of about 50,000 to SGILOGO revolutions 'per minute, it is unavoidable that vibrations occur which not only result in loud undesirable noises but also make satisfactory support of the shaft extremely diicult.

In order to avoid these disadvantages, according to the Vinvention it is proposed to 4arrange the air turbine interchangeably in the vicinity of the nose part yof the handpiece jointly with the ball bearings for the turbine rotor. It is particularly expedient for the turbine to be inserted `interchangeably in the rear end of the removable nose part.

` t, According tothe invention the air turbine can also lbe arranged in the vicinity of the nose part in the case of a handpiece which is not divided in the longitudinal and transverse senses. In this case, the turbine is interchangeably inserted into the handpiece from the rear end thereof.

Also, according to the invention,

in la handpiece with a removable nose part, the turbine can be so inserted in `the front end of the handle that it can -be removed in the forward direction once the nose part of the handpiece has been removed.

The arrangement of the air turbine in the vicinity of the nose part of the handpiece necessitates a driving shaft of only short lengt-h; therefore, vibration can be almost `completely eliminated at this shaft. The handpieces constructed according to the invention can run substantially more quietly and can `also be provided with more satisfactory bearings despite the high rotational speeds involved. i

It is expedient for the air turbine to be constructed as `an axial-admission turbine since, if the turbine is conin which:

FIGURE l is :a longitudinal sectional view of a handpiece wherein the turbine is interchangeably inserted in Vthe rear end of a removable nose part,

FIGURE 2 is a diagrammatic side view of the turbine rotor with front and rear annular discs,

FIGURE 3 is a rear view of the front annular disc or "a front View of the rear rannular disc,

FIGURE 4 is across-sectional view of the handpiece taken on the line IV-IV of FIGURE l,

lFIGURE 5 is a cross-sectional view of the handpiece f taken on the line V-V of FIGURE 1,

31176267. Patented Feb. 5, 1963 ICC FIGURE 6 is a longitudinal sectional viewof a modiiied form `of embodiment of a handpiece which is not divided either in the longitudinal or transverse senses, but is provided with a turbine inserted interchangeably from the rear end of the handpiece up to the vicinity of the nose part thereof, the cross-sections on lines IV- IV and V-V of FIGURE 6 corresponding to FIGURES 4 and 5, respectively,

FIGURE 7 is a longitudinal sectional view of a further form of embodiment of a handpiece wherein the turbine is so arranged in the front end of the handle tube that the turbine can be removed in the forward direction after the nose part of the handpiece has been removed,

FIGURE 8 is a cross-sectional view of the handpiece taken on the line VIII--VIII of FIGURE 7, and

FIGURE 9 is a cross-sectional view of a handpiece taken on the line IX-IX of FIGURE 7.

The form of embodiment according to FIGURES l to 5, comprises a handpiece having a handle tube 1 into the front end of which a nose part 2 of the handpiece is screwed at 3. Two ball bearings 5, 6 are arranged in the front portion of the nose part at a speciiic distance from one another which is determined by a spacer sleeve d. The inner races of these ball bearings are fitted onto the turbine shaft 7. The turbine shaft has a thickened or enlarged diameter rear end portion which carries a turbine rotor 8 the outer periphery of which is provided, as shown in FIGURE 2, with curved blades 9 extending in the axial direction. The turbine rotor 3 is surrounded by a turbine casing I0.

A front closure cap I1 is inserted in the front end of the turbine casing l@ and a rear closure cap l2 is inserted in the rear end of the casing. Situated within and centered by the front closure cap Il is an annular disc I3 which is provided at its outer periphery with a plurality of air ducts I4 which extend obliquely to the axis of the turbine. Arranged within the rear closure cap I2 and centred thereby is a rear annular disc 15 which in its turn is also provided at its outer periphery with a plurality of ducts I6 arranged obliquely to the axis of the turbine. The front and rear closure caps `are secured yagainst axial displacement in the turbine casing by flanging-over of the free ends of the turbine casing at I7. The front closure cap I1 of the turbine casing extends as far as the rear end of the outer race of the ball bearing 6. Situated between the outer wall of the turbine casing Ill and the inner wall of the handpiece nose part 2 is a free annular space I@ which is used for returning the turbine discharge air, as will be described hereinafter.

A. sleeve I9 is screwed into the rear annular disc 15. Situated between a collar 2d at the rear end of the sleeve I9 andthe free rear end of the rear closure cap I2 there is arranged a ring 21 which is provided with a plurality of axial holes 22 distributed about its periphery. The ring 21 is used for centering the sleeve 19 with respect to the inner wall of the handpiece nose part 2. Bearing in Huid-tight manner against an internal cone at the rear end of the sleeve I9, is an air supply pipe 23 which is arranged centrally within the handle tube l of the handpiece. The air supply pipe has a thickened or enlarged diameter rear end portion 24 provided with a lateral stub pipe 2d to which an air supply hose can be connected.

The air supplied through this stub pipe 26 passes through the air supply pipe 23 into the cavity 27 in the sleeve 19 and through radial holes 28 in the wall of the sleeve, through the oblique ducts I6 in the rear annular disc I5, into the turbine rotor 3. The air discharged from the turbine flows out through the oblique ducts 14 in the front annular disc I3 and then through the radial holes Z9 in the front closure cap Il, through the annular space 18 between the handpiece nose part and the turbine caslThis chuck 33 is formed o elastic material.

lfrom the front end the handle tube It.

.Then the ball bearings ing and through the axial holes 22 of the ring 21 into an annular space fl@ between the handle tube l and the air supply pipe Z3. rl`hen, from the annular space 3d, the air passes out through axial holes 3l (see also FGURE.

5) in the rear thickened end portion 2d of the air supply pipe 23, into the atmosphere.

Some of the turbine discharge air after flowing through the oblique ducts ftd in the front annular disc i3 and after passing through the ball bearings 5 and 6, reaches the tool of the instrument through nozzles 31?, which are arranged in a circle about the periphery of ne front end of the nose part.

A self-locking chuck 33 for the tool shank (not shown) is inserted in the front hollow end of the turbine shaft 7. The rear end of the chuck is provided with slots 34. ri'he tongues situated between the slots 3d are curve; slightly7 inwards. When the tool shank is inserted in the collet, the elastic tongues are pressed outwardly, and the tool shank is held fast by the elastic elfect produced thereby.

Provided within the air supply pipe 23 for the purpose of removing the tool shank from the chuck 33:, is a push rod 35 whose rear thickened end 3o, projecting from the rear end of the haudpiece, is held in a rear or retracted position by means of a spring 37 which surrounds the rear end of the push rod 35. The front end of the spring 37 bears against the end 3S of a sleeve 39 whose thiclzened rear end 4d is screwed at il into the rear thickened end 24 of the air supply pipe 23. The rear or retracted position of the push rod S5 is defined by an abutment disc 42 which bears on the end 33 of the sleeve 39. The front end of the push rod 35 is centered in a bore of the sleeve i, and, when the push rod is not being operated, terminates approximately' at the forward end face of the sleeve l?. A further push rod 43 is mounted for axial movement elastically in front of the push rod 55 within the hollow turbine shaft 7. The rear thickened end of this further push rod is urged by a spring 45 against a d6 which is inserted lixedly in the rear hollow end of the turbine shaft 7. The front end of the second push rod i3 is guided in a bore in the turbine shaft 7 and extends approximately as far as the rear end of the tool shank (not shown) which is inserted in the chuck 33. For ejecting the tool from the chuck 33, it is merely necessary for the push rod 3S to be pushed forwards by pressure on the rear end of its thickened end portion 35 in opposition to the action of the spring 37. Then the front end of the push rod 35 presses on the thickened rear end led of the push rod and the tool shank is pushed out of the chuck by the front end of the push rod y 43. The two push rods 35 and d3 return to their initial positions as a result of the action of the springs 37 and AS.

The form of embodiment according to FIGURE 6 corresponds to a considerable extent to the form of ernbodiment according to FiGURES l to 5. Like parts are designated with refere ce nurr rals.

This form of embodiment daders from the form of erubodirnent according to PGURES l to 5 in that the nose part 2 of the handpiece is not arranged to be detachable in this form of embodiment, the air supply pipe Z13 extends right up to a short distance front the rear end of the turbine shaft 7. The rear annular disc l5 is screwed on to the front end of the air supply pipe 2-3. Arranged between the rear end of the rear closure cap l2 and a collar of the air supply pipe 23 is the annular disc 2l which is also provided with axial holes Gtherwise the construction of the handpiece shown in FIGURE 6 corresponds to the form of embodiment according to FGURES l to 5.

When the rear thickened end 2d of the air supply pipe 23 is screwed oit, the air turbine with turbine shaft 7 and ball bearings 5 and 6 can be pulled out rearwardly from the handle tube together with the air supply pipe 2.3. and 6 can be removed in the forward direction from the turbine shaft 7 and it necessary replaced by new bearings.

In the form of embodiment according to FIGURES 7 to 9, 47 is the handle tube and 48 is the handpicce nose part which is screwed removably into the front end of the handle tube 47. The air turbine is inserted in the front end of the handle tube 47. The turbine rotor 50, which in accordance with FIGURE 2 is provided at its outer periphery with curved blades 5l (FIGURE 8) sits on the urbine shaft 52 which extends up to the front end of the nose part i8 of the handpiece. The turbine casing 53 is centred by the inner wall of the front end of the handle tube 47. Inserted in the front end of the turbine casing S3 is an annular disc 5ftwhich is provided at its outer periphery with ducts 55 extending obliquely relatively to the axis. The annular disc 54 is held in the turbine casing by a front closure cap 56 having a tubular extension 57 which extends as far as the rear end of the front ball bearing 53. The outer race of the front ball bearing 58 is held centred in the nose part 43 of the handpiece. The front closure cap 56 is tixed to the turbine casing 53 by hanging-over the front end of the turbine casing at 59. Inserted in the rear end of the turbine casing 53 is the rear annular disc 60 which is provided at its outer periphery with ducts 6l disposed obliquely to the axial direction of the turbine shaft. At the rear, the rear annular disc 60 is followed by the rear closure cap 62, which is connected to the turbine casing 53 by the hanging-over of the free rear end of the said casing at 63. Arranged between the turbine rotor 50 and the rear end of the rear closure cap 62 is the rear ball bearing 64 whose inner race sits on the hollow turbine shaft 52.

The rear closure cap 62 also carries, in a recess of its rear end face, an annular rubber packing 65 whose rear end face bears with a sealing-type action against the front face of the spacer ring 66 which centres the front end of the centrally arranged air discharge pipe 67 with espect to the handle tube 47. rhe outer periphery of the spacer ring 65 is provided with axial slots 68, the signicance of which will be described hereinafter.

The air discharge pipe 67 extends as far as the rear end of the handpece. A closure cap 69 is screwed at 70 into the rear end of the handpiece. A further threaded cap 7l, the bore of which serves to centre the rear end of the air discharge pipe 67, is screwed into a hole in the bottom of the closure cap 69. A rubber packing 72 is also provided between the closure cap 69 and the closure cap 7l. The air supply stub pipe 74 is inserted at an inclination into the closure cap 69 through the side thereof to debouch into the chamber 73 in the said cap.

The air supplied through the stub pipe 74 passes through the annular chamber 73 and the annular chamber 75 between the air discharge pipe 67 and handle tube e7, through the axial slots 68 of the spacer ring 65, through radial holes 76 in the rear closure cap 62 and the inclined ducts 6l of the rear disc di), into the turbine rotor 59.

The discharged air is guided through the inclined ducts of the front annular disc 54 into the annular chamber 77 within the front closure cap and passes through radial apertures 7S in the hollow turbine shaft 52 through the hollow interior of the turbine shaft and the air discharge pipe 67 adjoining said turbine shaft at the rear thereof, and out into the atmosphere at the rear end of the handpiece.

Some of the turbine discharge air passes through the `annular chamber 79 between the turbine shaft 52 and the tubular extension 57 of the front closure cap 56 through the front ball bearing 53 and through peripherally disposed nozzles 8@ in the nose part of the handpiece to reach the tool which is inserted in the handpiece.

As in the form of embodiment according to FIGURES l to 5, a self-locking chuck 8l for the tool shank (not shown) is inserted in the front hollow end of the turbine shaft 52. This chuck -81 which is made of elastic. material is provided at its rear end with slots 82. The tongues situated between the slots 82 are slightly curved in the inward direction. When the tool shank is inserted in the chuck, the elastic tongues are pressed outwards, and the Iresulting spring action holds the tool shank fast.

A push rod 83 is arranged within the front end of the hollow turbine shaft 52 to permit removal of the tool shank from the chuck 81. The rear thickened end 84 of this push rod bears by means of the spring 85 on the ring 86 which is fixed in the hollow turbine shaft 52 somewhat in front of the apertures 78. The front end of the spring-loaded push rod 83 is guided in a bore in the turbine `shaft 52 and extends approximately as far as the rear `end of the tool shank (not shown)` which is inserted in the chuck 81.

In order to eject the tool `from the chuck 81, the push rod 83 is pressed forwardly in opposition to the action of the spring 85 by means of a hand rod which can be inserted through the hollow discharge pipe 67 from the -rear end of the handpiece.

What is claimed is:

l. ln an air driven dental drill including an elongated hollow handpiece provided at one end with a nose portion and having inlet and outlet means at the other end for -motive air, shaft means including concentric rotor means at one end thereof and being provided with means at the other end to removably secure a dental bur therein, casing means to enclose said rotor, said casing including inlet and outlet means for motive air and also including air deliecting means withinsaid casing at one end to direct air generally unidirectionally longitudinally into operative engagement with said rotor, anti-friction bearing means for said shaft, means to removably position said bearing means and said rotor casing within said handpiece adjacent said one end, said handpiece being comprised of at least two separable elements, one of said elements including conduit means for separable connection between the inlet and outlet means of said handpiece and the inlet v-and outlet means of said rotor casing, one of said elements being separable from the other to permit removal of said rotor casing shaft means and bearing means as a unit.

2. The invention as defined in claim l, wherein said means to direct air into operative engagement with said,4 rotor includes longitudinally extending passage means axially adjacent one end of said rotor in communication with the inlet means of the casing, said outlet means of the casing being in communication with the other end of the rotor, whereby motive fluid travels axially of the rotor.

3. The invention as defined in claim 1, wherein one of the separable elements of the handpiece comprises a nosepiece, and said means to removably position said bearing means and said rotor casing are both contained within said nosepiece, said rotor casing shaft means and bearing means being removable from said nosepiece as a unit.

4. The invention as defined in claim 1, wherein said means to direct air within the rotor casing includes two discs, positioned one at each end of the rotor, said discs being provided with a plurality of angularly disposed pa-ssages to induce an axial twist to said motive air.

5. The invention as defined in claim 1, wherein said rotor casing means is provided with a central opening at one end for motive air and said handpiece is provided with a concentrically arranged conduit extending between said opening and said other end of the handpiece, said conduit being joined to said rotor casing means at one end and separably connected to the handpiece at said other end of the handle to permit removal of said conduit, rotor casing means, shaft means and bearing means as a unit.

6. The invention as defined in claim 1, wherein said rotor casing is provided with a central opening at one end formotive air and said handpiece is provided with a concentrically arranged conduit means extending between said opening and said other end of the handpiece, and coupling means is provided'to establish communication between said conduit means and said opening, said coupling means including a conically formed element, said conduit means being detachably removable from said other end of the handpiece.

7. The invention as defined in claim 1, wherein said separable elements of the handpiece comprise a tubular handle portion and hollow nosepiece, said rotor casing being received and positioned within said handle portion, said rotor casing shaft means and bearing means being removable from said handle portion as a unit.

8. The invention as defined in claim 1, wherein said anti-friction bearing means includes two bearings, one disposed at the forward end of the shaft means, the other bearing being contained within the rotor casing means.

9. The invention as defined in claim 3, wherein said means to position said casing includes an annular seat provided on the inner wall of the nose portion, the forward end of said rotor casing being adapted to engage with -said annular seat, the rear end of said casing being provided with an annularly projecting ring to engage with the inner surface of the nosepiece axially spaced from said seat, said casing having said inlet and outlet for motive air at opposite ends and being of less diameter than the interior of said nose portion to provide an annular passage for said air.

10. The invention as defined in claim 6, wherein said conduit means comprises one of the separable elements of the handpiece to permit removal of said rotor casing shaft means and bearing means as a unit.

11.` The invention as defined in claim 6, wherein said conduit means includes an additional passage means in communication with the interior of the handpiece.

l2. The invention as defined in claim 7, wherein said l bearing means includes an anti-friction bearing at the forward end of the shaft means, and said nosepiece is provided with an annular seat to receive and removably position said anti-friction bearing.

13. The invention as defined in claim 8, wherein the bearing contained within the rotor casing is disposed at the rear end of the shaft means.

14. A dental handpiece comprising an elongated handle tube having a nose portion coaxial therewith at the front end thereof, an air turbine unit removably positioned within at least the front end portion of said handle tube and comprising in combination: a shaft rotatable coaxially within said nose portion, bearings carried by and spaced longitudinally of said shaft, means on the end of said shaft nearest the front end of said handpiece to receive a dental tool, and a turbine rotor fixed to said shaft adjacent the opposite end thereof and having impeller blades on the exterior thereof and extending substantially longitudinally along said rotor; and air conducting means in said handle tube extending generally longitudinally thereof from the rear end of said handle tube to the rearward ends of said impeller blades to direct air engageably with said blades generally unidirectionally longitudinally along said blades, to the front ends thereof, thereby to rotate said rotor, said handle tube an-d nose portion thereof having connected portions separable to permit removal of said air turbine unit as an assembly longitudinally therefrom.

15. The invention as defined in claim 14, wherein said air conducting means includes a disc-shaped member being positioned axially with respect to the rotor means, said member being provided with axially extending passages.

16. The invention as defined in claim 15, wherein said air conducting means includes conduit means disposed within the rear of the handle tube, and a cylindrical housing is provided to enclose said rotor and disc-shaped member, said housing having an opening adapted to separably connect with said conduit means.

aereas? 17. The invention as defined in claim 16, wherein said leans to separably connect said conduit means with said housing includes a dat resilient gasket member adapted to be interposed between the abutting ends of `the conduit t means and the opening in the rotor housing, and a radially extending member is connected at the one end of said conduit means to position said conduit means for said abutting engagement.

18. in an air driven dental handpieco including an elongated tubular member having a nose portion at one end and inlet and outlet connections for motive air at the other end, cylindrical rotor means including concentric hollow shaft means, bearing means for the shaft means to position said rotor means concentrically in said tubular member, said rotor means being provided with blade means positioned to be operative in response to motive air moving in an axial direction, conduit means disposed in said tubular member `for communication between the rearward end of the hollow shaft and one of the motive air connections at the other end of the tubular member, said hollow shaft means being provided with a radial passage adjacent one end o the rotor means, passage means disposed at the other end of the rotor means in communicatio-n with the interior of the tubular member and the other of said motive air connections at the other end of the tubular member.

19. The invention as defined in claim 18, wherein said rotor means is enclosed Within a cylindrical housing, said housing having a radially extending cap means closing one end tl ereof, said cap means including a concentric opening in alignment with said hollow shaft, said cap means also having a peripherally disposed opening in communication with the interior of the tubular member and `the space surrounding the rotor blade means.

20. An air operated dental handpiece comprising, a hollow handle containing an air supply pipe, a nose portion having a bur receiving end and connected to said ings rotatably supporting said shaft in said nose portion, said Vshaft having a bur receiving recess therein, a spring mounted rod axially supported in said pipe extending through said handle and into lsaid recess, said turbine casing being centered by means of a closure cap in the bore of the nose portion of the handpiece and the rear end thereof being centered by means of a closure cap on the front end of said pipe, said pipe being in turn centered by means of a ring on the rear end of the inner wall of the nose portion, said turbine casing and said lnose portion dening an annular space therebetween for return of air discharged by said turbine.

21. in a fluid turbine driven dental drill, including a tubular handpiece, a turbine rotor including a hollow shaft, one end of said shaft being provided with frictional coupling means to removably receive a dental bur, said handpiece being provided with aligned openings at either end thereof, means to rotatably mount said shaft to position said coupling means .adjacent one of the openings in the tubular handpiece, a 'rst push rod slidable in said hollow shaft and movable in one direction to eject a bur, biasing means to urge said rod in `the opposite direction, stop means to limit movement ofthe rod in said opposite direction, a second push rod slidablyV positioned within the handpiece in alignment with the lirst push rod, one end of the second push rod projecting outwardly from the other end of the handpiece, said second push rod being movable in one direction to actuate the iirst push rod, biasing means to urge the second push rod in the opposite direction, and stop means to limit movement of the second push rod in said opposite direction.

References Cited in the tile of this patent UNITED STATES PATENTS 1,419,140 Hutchinson June 13, 1922 2,180,993 Monnier Nov. 21, 1939 2,793,437 Vtilson May 28, 1957 2,799,934 Kern Iuly 23, 1957 2,945,299 Fritz Iuly l9, 1960 FOREIGN PATENTS 357,117 Germany Aug. 15, 1922 456,128 Germany Sept. 15, 1928 

1. IN AN AIR DRIVEN DENTAL DRILL INCLUDING AN ELONGATED HOLLOW HANDPIECE PROVIDED AT ONE END WITH A NOSE PORTION AND HAVING INLET AND OUTLET MEANS AT THE OTHER END FOR MOTIVE AIR, SHAFT MEANS INCLUDING CONCENTRIC ROTOR MEANS AT ONE END THEREOF AND BEING PROVIDED WITH MEANS AT THE OTHER END TO REMOVABLY SECURE A DENTAL BUR THEREIN, CASING MEANS TO ENCLOSE SAID ROTOR, SAID CASING INCLUDING INLET AND OUTLET MEANS FOR MOTIVE AIR AND ALSO INCLUDING AIR DEFLECTING MEANS WITHIN SAID CASING AT ONE END TO DIRECT AIR GENERALLY UNIDIRECTIONALLY LONGITUDINALLY INTO OPERATIVE ENGAGEMENT WITH SAID ROTOR, ANTI-FRICTION BEARING MEANS 